U.S. patent number 4,434,299 [Application Number 06/440,927] was granted by the patent office on 1984-02-28 for production of aromatic amines using crystalline silicate catalysts.
This patent grant is currently assigned to Mobil Oil Corporation. Invention is credited to Clarence D. Chang, William H. Lang.
United States Patent |
4,434,299 |
Chang , et al. |
February 28, 1984 |
Production of aromatic amines using crystalline silicate
catalysts
Abstract
A process for the preparation of aniline by reaction of
alicyclic alcohols or ketones with ammonia in the presence of a
crystalline silicate catalyst having the structure of ZSM-5.
Especially preferred alicyclic charge stocks are the mononuclear
naphthenic type compounds such as cyclohexanol and cyclohexanone or
mixtures thereof.
Inventors: |
Chang; Clarence D. (Princeton,
NJ), Lang; William H. (Richmond, VT) |
Assignee: |
Mobil Oil Corporation (New
York, NY)
|
Family
ID: |
23750769 |
Appl.
No.: |
06/440,927 |
Filed: |
November 12, 1982 |
Current U.S.
Class: |
564/396; 564/397;
564/402; 564/446; 564/447 |
Current CPC
Class: |
C07C
209/18 (20130101); C07C 209/22 (20130101); C07C
209/18 (20130101); C07C 211/46 (20130101); C07C
209/22 (20130101); C07C 211/46 (20130101) |
Current International
Class: |
C07C 085/06 ();
C07C 085/02 () |
Field of
Search: |
;564/396,397,402,446,447 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Shaver; Paul F.
Attorney, Agent or Firm: McKillop; Alexander J. Speciale;
Charles J.
Claims
What is claimed is:
1. In a process for the production of aromatic amines by reaction
of alicyclic alcohols, ketones and mixtures thereof with ammonia in
the presence of a catalyst, the improvement which comprises
utilizing as a catalyst a crystalline silicate zeolite having a
silica to alumina ratio of at least about 12 and a constraint index
of about 1 to 12.
2. The process of claim 1 wherein said zeolite is characterized by
a silica/alumina ratio in excess of 30.
3. The process of claim 1 wherein said reaction is carried out at a
temperature between about 150.degree. C. and about 650.degree.
C.
4. The process of claim 1 wherein the crystalline silicate is
ZSM-5.
5. The process of claim 1 wherein said alcohol is cyclohexanol.
6. The process of claim 1 wherein said ketone is cyclohexanone.
7. The process of claims 2, 3, 4, 5 or 6 wherein the crystalline
silicate is dispersed in a matrix.
8. The process of claims 2, 3, 4, 5 or 6 wherein the crystalline
silicate is usd in intimate combination with a hydrogenating
component.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production of aromatic
amines such as aniline by reaction of an alicyclic alcohol or
ketone with ammonia in the presence of a crystalline silicate
catalyst.
2. Description of the Prior Art
The reaction of alcohols and ketones with ammonia in the vapor
phase to produce amines is well known. One usually gets a mixture
of primary, secondary and tertiary amines and water. The proportion
of the various amines produced can be varied somewhat by the ratio
of alcohol or ketone to ammonia in the feed, i.e., large ratios
give tertiary amines while low ratios tend to give primary amines.
Temperatures of 300.degree.-500.degree. C. and pressures of 10-200
atmospheres have been employed in carrying out such reactions in
the presence of various catalysts, such as alumina. Aluminum
phosphate has been used as a catalyst to prepare isopropyl amines
from ammonia and isopropyl alcohol at 200 atm pressure and a
temperature of 350.degree. C. This reaction is described in British
Pat. No. 649,980. Amines have also been produced from alcohols,
ammonia and hydrogen over hydrogenation catalysts. It has been
reported that mono-, di-, and tributylamines have been prepared
from n-butyl alcohol, ammonia and hydrogen at 190.degree. C. over a
pelletized nickel catalyst. U.S. Pat. No. 4,191,709 discloses a
process for the preparation of an amine by reaction of methanol
with ammonia in the presence of zeolite FU-1 catalyst. U.S. Pat.
No. 4,229,374 describes a process for making tertiary amines by
reacting alicyclic alcohols, aldehydes or ketones with ammonia. The
catalyst comprises copper, tin and alkali metal supported on a
suitable carrier such as alumina. U.S. Pat. No. 4,082,805 discloses
the reaction of a C.sub.1 -C.sub.5 alcohol or ether with ammonia in
the presence of a ZSM-5 type zeolite catalyst.
SUMMARY OF THE INVENTION
This invention provides a process for producing aromatic amines
such as aniline by reacting alicyclic alcohols or ketones with
ammonia in the presence of a specific catalyst by replacing the
hydrogen on the reactant ammonia with the hydrocarbon moiety of the
reactant alcohol or ketone. The catalyst comprises a crystalline
silicate zeolite suitably provided with a metal promoter having
dehydrogenation activity. This catalyst has the advantage of being
shape-selective for the production of aniline while suppressing the
formation of undesirable by-products such as diphenylamine and
carbazole.
The present process comprises contacting the noted reactants in the
presence of the specified catalyst at a temperature within the
approximate range of 150.degree. to 650.degree. C. and preferably
between about 175.degree. C. and about 250.degree. C. The pressure
during reaction is generally between atmospheric and 1000 psig and
the relative feed rates expressed as liquid hourly space velocity
of (1) alicyclic alcohol or ketone and (2) ammonia are within the
approximate range of 1:1 to 5:1 and preferably between about 2:1 to
4:1.
The reaction product comprises a mixture of aniline with secondary
and tertiary aromatic amines which can either be collected as a
combined amine product or separated into the respective mono,
secondary and tertiary components. In general, the secondary and
tertiary amines comprise a smaller fraction of the reaction
products as the size and molecular weight of the alcohol or ketone
reactant increases. The general reaction may be illustrated as
follows: ##STR1##
DESCRIPTION OF SPECIFIC EMBODIMENTS
The catalyst employed in this invention is prepared by compositing
a hydrogenation/dehydrogenation component with a particular
crystalline silicate zeolite. Compositing may be effected by
ion-exchange of the zeolite, by impregnation of the zeolite or by
other means which lead to an intimate association of the
hydrogenation/dehydrogenation component with the zeolite.
The particular crystalline zeolite utilized herein may be any
member of the novel class of zeolites now to be described. Although
these zeolites have unusually low alumina contents, i.e., high
silica to alumina ratios, they are very active even when the silica
to alumina ratio exceeds 30. The activity is surprising since
catalytic activity is generally attributed to framework aluminum
atoms and/or cations associated with these aluminum atoms. These
zeolites retain their crystallinity for long periods in spite of
the presence of steam or high temperature which induces
irreversible collapse of the framework of other zeolites, e.g., of
the X and A type. Furthermore, carbonaceous deposits, when formed,
may be removed by burning at higher than usual temperatures to
restore activity. These zeolites, used as catalysts, generally have
low coke-forming activity and therefore are conducive to long times
on stream between regenerations by burning with oxygen-containing
gas such as air.
An important characteristic of the crystal structure of this class
of zeolites is that it provides constrained access to and egress
from the intracrystalline free space by virtue of having an
effective pore size intermediate between the small pore Linde A and
the large pore Linde X, i.e., the pore windows of the structure
have about a size such as would be provided by 10-membered rings of
oxygen atoms. It is to be understood, of course, that these rings
are those formed by the regular disposition of the tetrahedra
making up the anionic framework of the crystalline aluminosilicate,
the oxygen atoms themselves being bonded to the silicon or aluminum
atoms at the centers of the tetrahedra. Briefly, the preferred type
zeolites useful in this invention possess, in combination: a silica
to alumina mole ratio of at least about 12; and a structure
providing constrained access to the crystalline free space.
The silica to alumina ratio referred to may be determined by
conventional analysis. This ratio is meant to represent, as closely
as possible, the ratio in the rigid anionic framework of the
zeolite crystal and to exclude aluminum in the binder or in
cationic or other form within the channels. Although zeolites with
a silica to alumina ratio of at least 12 are useful, it is
preferred to use zeolites having higher ratios of at least about
30. Such zeolites, after activation, acquire an intracrystalline
sorption capacity for normal hexane which is greater than that for
water, i.e., they exhibit "hydrophobic" properties. It is believed
that this hydrophobic character is advantageous in the present
invention.
The zeolites useful in this invention have an effective pore size
such as to freely sorb normal hexane. In addition, the structure
must provide constrained access to larger molecules. It is
sometimes possible to judge from a known crystal structure whether
such constrained access exists. For example, if the only pore
windows in a crystal are formed by 8-membered rings of oxygen
atoms, then access by molecules of larger cross-section than normal
hexane is excluded and the zeolite is not of the desired type.
Windows of 10-membered rings are preferred, although in some
instances excessive puckering of the rings or pore blockage may
render these zeolites ineffective. 12-membered rings usually do not
offer sufficient constraint to produce the advantageous
conversions, although the puckered 12-ring structure of TMA
offretite shows constrained access. Other 12-ring structure may
exist which, due to pore blockage or to other cause, may be
operative.
Rather than attempt to judge from crystal structure whether or not
a zeolite possesses the necessary constrained access to molecules
larger than normal paraffins, a simple determination of the
"Constraint Index" as herein defined may be made by passing
continuously a mixture of an equal weight of normal hexane and
3-methylpentane over a small sample, approximately one gram or
less, of zeolite at atmospheric pressure according to the following
procedure. A sample of the zeolite, in the form of pellets or
extrudate, is crushed to a particle size about that of coarse sand
and mounted in a glass tube. Prior to testing, the zeolite is
treated with a stream of air at 1000.degree. F. for at least 15
minutes. The zeolite is then flushed with helium and the
temperature is adjusted between 550.degree. F. and 950.degree. F.
to give an overall conversion between 10% and 60%. The mixture of
hydrocarbons is passed at 1 liquid hourly space velocity (i.e., 1
volume of liquid hydrocarbon per volume of zeolite per hour) over
the zeolite with a helium dilution to give a helium to total
hydrocarbon mole ratio of 4:1. After 20 minutes on stream, a sample
of the effluent is taken and analyzed, most conveniently by gas
chromatography, to determine the fraction remaining unchanged for
each of the two hydrocarbons.
The "Constraint Index" is calculated as follows: ##EQU1##
The Constraint Index approximates the ratio of the cracking rate
constants for the two hydrocarbons. Zeolites suitable for the
present invention are those having a Constraint Index of 1 to 12.
Constraint Index (CI) values for some typical zeolites are:
______________________________________ CAS C.I.
______________________________________ ZSM-4 0.5 ZSM-5 8.3 ZSM-11
8.7 ZSM-12 2 ZSM-23 9.1 ZSM-35 4.5 ZSM-38 2 TMA Offretite 3.7 Beta
0.6 H--Zeolon (mordenite) 0.4 REY 0.4 Amorphous Silica-Alumina 0.6
Erionite 38 ______________________________________
The above described Constraint Index is an important and even
critical definition of those zeolites which are useful in the
instant invention. The very nature of this parameter and the
recited technique by which it is determined, however, admit of the
possibility that a given zeolite can be tested under somewhat
different conditions and thereby have different Constraint Indexes.
Constraint Index seems to vary somewhat with severity of operation
(conversion) and the presence or absence of binders. Therefore, it
will be appreciated that it may be possible to so select test
conditions to establish more than one value in the range of 1 to 12
for the Constraint Index of a particular zeolite. Such a zeolite
exhibits the constrained access as herein defined and is to be
regarded as having a Constraint Index of 1 to 12. Also contemplated
herein as having a Constraint Index of 1 to 12 and therefore within
the scope of the novel class of highly siliceous zeolites are those
zeolites which, when tested under two or more sets of conditions
within the above-specified ranges of temperature and conversion,
produce a value of the Constraint Index slightly less than 1, e.g.,
0.9, or somewhat greater than 12, e.g., 14 or 15, with at least one
other value of 1 to 12. Thus, it should be understood that the
Constraint Index value as used herein is an inclusive rather than
an exclusive value. That is, a zeolite when tested by any
combination of conditions within the testing definition set forth
hereinabove to have a Constraint Index of 1 to 12 is intended to be
included in the instant catalyst definition regardless that the
same identical zeolite tested under other defined conditions may
give a Constraint Index value outside of 1 to 12.
The class of zeolites defined herein is exemplified by ZSM-5,
ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, and other similar
materials. U. S. Pat. No. 3,702,886 describing and claiming ZSM-5
is incorporated herein by reference.
ZSM-11 is more particularly described in U.S. Pat. No. 3,709,979,
the entire content of which is incorporated herein by
reference.
ZSM-12 is more particularly described in U.S. Pat. No. 3,832,449,
the entire content of which is incorporated herein by
reference.
ZSM-23 is more particularly described in U.S. Pat. No. 4,076,842,
the entire content of which is incorporated herein by
reference.
ZSM-35 is more particularly described in U.S. Pat. No. 4,016,245,
the entire content of which is incorporated herein by
reference.
ZSM-38 is more particularly described in U.S. Pat. No. 4,046,859,
the entire content of which is incorporated herein by
reference.
The specific zeolites described, when prepared in the presence of
organic cations, are substantially catalytically inactive, possibly
because the intracrystalline free space is occupied by organic
cations from the forming solution. They may be activated by heating
in an inert atmosphere at 1000.degree. F. for one hour, for
example, followed by base exchange with ammonium salts followed by
calcination at 1000.degree. F. in air. The presence of organic
cations in the forming solution may not be absolutely essential to
the formation of this type zeolite; however, the presence of these
cations does appear to favor the formation of this special class of
zeolite. More generally, it is desirable to activate this type
catalyst by base exchange with ammonium salts followed by
calcination in air at about 1000.degree. F. for from about 15
minutes to about 24 hours.
Natural zeolites may sometimes be converted to this type zeolite
catalyst by various activation procedures and other treatments such
as base exchange, steaming, alumina extraction and calcination, in
combinations. Natural minerals which may be so treated include
ferrierite, brewsterite, stilbite, dachiardite, epistilbite,
heulandite, and clinoptilolite. The preferred crystalline
aluminosilicates are ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, and
ZSM-38, with ZSM-5 being particularly preferred.
In a preferred aspect of this invention, the zeolites hereof are
selected as those having a crystal framework density, in the dry
hydrogen form, of not less than about 1.6 grams per cubic
centimeter. It has been found that zeolites which satisfy all three
of these criteria are most desired for several reasons. When
hydrocarbon products or by-products are catalytically formed, for
example, such zeolites tend to maximize the production of gasoline
boiling range hydrocarbon products. Therefore, the preferred
zeolites of this invention are those having a Constraint Index as
defined above of about 1 to 12, a silica to alumina ratio of at
least about 12 and a dried crystal density of not less than about
1.6 grams per cubic centimeter. The dry density for known
structures may be calculated from the number of silicon plus
aluminum atoms per 1000 cubic Angstroms, as given, e.g., on Page 19
of the article on Zeolite Structure by W. M. Meier. This paper, the
entire contents of which are incorporated herein by reference, is
included in "Proceedings of the Conference on Molecular Sieves,
London, Apr. 1967," published by the Society of Chemical Industry,
London, 1968. When the crystal structure is unknown, the crystal
framework density may be determined by classical pyknometer
techniques. For example, it may be determined by immersing the dry
hydrogen form of the zeolite in an organic solvent which is not
sorbed by the crystal. Or, the crystal density may be determined by
mercury porosimetry, since mercury will fill the interstices
between crystals but will not penetrate the intracrystalline free
space. It is possible that the unusual sustained activity and
stability of this class of zeolites is associated with its high
crystal anionic framework density of not less than about 1.6 grams
per cubic centimeter. This high density must necessarily be
associated with a relatively small amount of free space within the
crystal, which might be expected to result in more stable
structures. The free space, however, is important as the locus of
catalytic activity.
Crystal framework densities of some typical zeolites including some
which are not within the purview of this invention are:
______________________________________ Void Framework Zeolite
Volume Density ______________________________________ Ferrierite
0.28 cc/cc 1.76 g/cc Mordenite .28 1.7 ZSM-5, -11 .29 1.79
Dachiardite .32 1.72 L .32 1.61 Clinoptilolite .34 1.71 Lauminite
.34 1.77 ZSM-4 (Omega) .38 1.65 Heulandite .39 1.69 P .41 1.57
Offretite .40 1.55 Levynite .40 1.54 Erionite .35 1.51 Gmelinite
.44 1.46 Chabazite .47 1.45 A .5 1.3 Y .48 1.27
______________________________________
When synthesized in the alkali metal form, the zeolite is
conveniently converted to the hydrogen form, generally by
intermediate formation of the ammonium form as a result of ammonium
ion exchange and calcination of the ammonium form to yield the
hydrogen form. In addition to the hydrogen form, other forms of the
zeolite wherein the original alkali metal has been reduced to less
than about 0.5 percent by weight may be used. Thus, the original
alkali metal of the zeolite may be replaced by ion exchange with
cobalt, but other suitable ions of Groups IB to VIII of the
Periodic Table, including, by way of example, nickel, copper, zinc,
palladium, calcium or rare earth metals, also may be present.
The crystalline zeolite catalyst is used in intimate combination
with a hydrogenating component such as tungsten, iron, vanadium,
molybdenum, rhenium, nickel, cobalt, chromium, manganese, or a
noble metal such as platinum or palladium where a
hydrogenation/dehydrogenation function is to be performed. Such
component can be exchanged into the composition, impregnated
therein or physically intimately admixed therewith. Such component
can be impregnated in or on the zeolite, such as, for example, by,
in the case of platinum, treating the zeolite with a platinum
metal-containing ion. Thus, suitable platinum compounds include
chloroplatinic acid, platinous chloride and various compounds
containing the platinum amine complex.
The compounds of the useful platinum or other metals can be divided
into compounds in which the metal is present in the cation of the
compound and compounds in which it is present in the anion of the
compound. Both types of compounds which contain the metal in the
ionic state can be used. A solution in which platinum metals are in
the form of a cation or cationic complex, e.g., Pt(NH.sub.3).sub.6
Cl.sub.4 is particularly useful.
The amount of the hydrogenation/dehydrogenation component employed
is not critical and may range from about 0.01 to about 30 weight
percent, preferably 0.1 to 0.5 weight percent, based on the entire
catalyst.
In practicing the process of the invention, it may be desirable to
incorporate the zeolite in another material resistant to the
temperatures and other reaction conditions employed. Such matrix
materials include synthetic or naturally occurring substances as
well as inorganic materials such as clay, silica and/or metal
oxides. The latter may be either naturally occurring or in the form
of gelatinous precipitates or gels including mixtures of silica and
metal oxides. Naturally occurring clays which can be composited
with the modified zeolite include those of the montmorillonite and
kaolin families, which families include the subbentonites and the
kaolins commonly known as Dixie, McNamee-Georgia and Florida clays
or others in which the main mineral constituent is halloysite,
kaolinite, dickite, nacrite or anauxite. Such clays can be used in
the raw state as originally mined or initially subjected to
calcination, acid treatment or chemical modification.
In addition to the foregoing materials, the zeolites employed
herein may be composited with a porous matrix materials, such as
silica-alumina, silica-magnesia, silica-zirconia, silica-thoria,
silica-berylia, silica-titania as well as ternary compositions,
such as silica-alumina-thoria, silica-alumina-zirconia,
silica-alumina-magnesia and silica-magnesia-zirconia. The matrix
may be in the form of a cogel. The relative proportions of finely
divided zeolite and inorganic oxide gel matrix may vary widely with
the zeolite content ranging from between about 1 to about 99
percent by weight and more usually in the range of about 5 to about
80 percent by weight of the composite. A particularly suitable
combination is one containing about 65 weight percent of the
zeolite in 35 weight percent of a relatively inactive alumina
matrix.
The charge stock can be any alicyclic ketone or alcohol wherein the
oxygen is directly connected to a ring carbon atom. By alicyclic is
meant a ring-type compound which is at least partially saturated,
and may be Mononuclear or polynuclear, that is containing from one
to four rings, in which the ring to which the oxygen atom is
attached is at least partially saturated. These alicyclic ketones
and alcohols include those compounds which contain from one to
three oxygen atoms each of which is directly connected to a ring
carbon atom. The preferred alicyclic compounds are the mononuclear
naphthenic type derivatives. The especially preferred charge stock
is cyclohexanone, cyclohexanol, and mixtures of the two. The ring
compounds can have one or more groups attached to the ring which do
not interfere with the amination reaction, such as lower alkyl
having from one to four carbon atoms, phenyl, benzyl, tolyl, xylyl,
etc. The charge stock compounds can suitably contain between 4 and
18 carbon atoms per molecule and preferably contain between 6 and
10 carbon atoms. Suitable charge stock compounds include the
following without being limited thereto: cyclohexanol,
cyclohexanone, cyclohexenol, cyclohexenone, 1,3-cyclohexanediol,
1,4-cyclohexanediol, 1,3-cyclohexanedione, 1,4-cyclohexanedione,
4-methylcyclohexanone, 4-t,butylcyclohexanol,
3,5-dimethylcyclohexanone, 4-phenylcycloexanone,
3-tolylcyclohexanone, cyclopentanol, cyclopentanone,
3-methylcyclopentanol, 2-ketotetralin, 2-(
1-cyclohexenyl)-cyclohexanone, 2,6-dicyclohexenylcyclohexanone,
etc.
It is preferred to carry out the reaction in the presence of
hydrogen. It is advantageous to use partial pressures of hydrogen
of from about 100 psi to about 1000 psi. It is advantageous to use
a hydrogen to alcohol or ketone molar ratio greater than one. The
reaction system may also be partially pressurized with inert gases
such as nitrogen, argon.
Inert diluents, such as aliphatic paraffins can be present in the
charge stock, if desired, but their presence merely utilizes needed
reactor space and reduces the space-time-yield of products.
Unsaturated compounds, such as acetylenes, linear or branched
olefins, and aromatic type compounds can be tolerated, but are
undesirable as they may tend to polymerize, hydrogenate or
adversely affect the equilibrium of the reaction.
Production of aromatic amines in the presence of the described
catalyst is effected by contact of ammonia with the alcohol or
ketone reactant at a temperature between about 150.degree. to about
650.degree. C. and preferably between about 175.degree. and about
250.degree. C. At the higher temperatures, the zeolites of high
silica/alumina ratio are preferred. For example, ZSM-5 of 30
SiO.sub.2 /Al.sub.2 O.sub.3 ratio and upwards is very stable at
high temperatures. The reaction generally takes place at
atmospheric pressure, but the pressure may be within the
approximate range of 1 atmosphere to 1000 psig. The relative feed
rates, expressed as liquid hourly space velocity of (1) alcohol or
ketone and (2) ammonia are generally within the approximate range
of 1:0 to 5:0 and preferably between about 1:0 to 4:0. The reaction
product may comprise predominately or solely a primary amine. In
those instances where some di- or triaromatic amines are formed,
together with the water of reaction, they may be separated by any
suitable means, such as by distillation or chromatographic
separation.
The following example will serve to illustrate the process of this
invention without limiting the same:
EXAMPLE
A nickel modified ZSM-5 catalyst having the composition 65% Ni
HZSM-5 (0.8% Ni) and 35% alumina binder was prepared and utilized
in the conversion of cyclohexanone to aniline at a temperature of
482.degree. C. and a pressure of 200 psig. The ammonia and
cyclohexanone reactants were introduced into a reactor of the
downflow type at liquid hourly space velocities of 1.3 and 1.0,
respectively. The data from this example is set forth below:
______________________________________ Cyclohexanone Conversion
99.8% Product Distribution Wt. %
______________________________________ Aniline 16.2 Diphenylaniline
2.8 Carbazole 1.3 Toluidines 0.9 Pyridines 1.7 Phenol 3.2
Alkylphenols 7.2 Ketones 1.1 Higher heterocyclics(a) 57.1
Hydrocarbons 8.5 100.0 ______________________________________
(a)Mainly 2phenylindole, 3methyl benzoquinoline, acridine.
* * * * *